House (4x4 Main Room): Pay 10,000 bells.
upgrade to 6x6 Main Room: 98,800 bells
upgrade to 8x8 Main Room: 198,000 bells
4x4 Second Floor: Pay 289,000 bells
upgrade to 6x6 second floor: 498,000 bells
upgrade to 8x8 second floor: 598,000 bells
4x4 Additional Rooms (left right, & back wall): Pay 348,000 bells
upgrade to 6x6 additional room: 498,000 bells
upgrade to 8x8 additional room: 598,000 bells
4x4 Basement: Pay 428,000 bells
upgrade to 6x6 basement: 498,000 bells
upgrade to 8x8 basement: 598,000 bells
[ The total cost to fully expand your house: 7,595,800 bells. ]
T&T Mart: Play for 7 days, upgrade tent to house, spend 12,000 bells / buy 15 items
Super T&T Mart: 10 days after you upgraded to T&T mart, 10 days after opening the Garden Store, and after spending 25,000+ bells.
Home Center: 21 days after you upgraded to Super T&T, spend 50,000+ bells
T&T Emporium: 30 days after you upgraded to Home Center, unlock Gracie, spend 100,000+ bells.
Cyrus: Play the game for 7 days, have 50+ pieces of furniture and 10+ pieces of clothing in your catalog, make 100,000+ bells by selling to Reese at Re-Tail.
Kicks: play for 10 days, spend 8,000+ bells at Able Sisters
Shampoodle: 7 days after Kicks has opened, spend 10,000+ bells at Kicks/Able sisters
Sable (for QRCodes): befriend her by speaking to her everyday for 16 days straight.
Gracie Grace: Spend 70,000+ bells at the Home Center. She will then appear by the town tree. She must approve of your fashion sense (to do this you must have your entire outfit matching) 4 times. Her store will not open until you have unlocked the T&T Emporium where it will be on the 3rd floor.
Garden Center: 5 days of playing, interact with 30 plant types: ie: shake 30 trees/plant 30 flowers/pull 30 weeds or a combination of the 3 (shake 10 trees, plant 10 flowers, pull 10 weeds, etc you get the point)
House of Fortune: Have Katrina tell you 20 fortunes
Club lol: Unlock Super T&T Mart, 5 days after Shrunk asks you to gather signatures.
Museum Second Floor: donate 20 items (note it must be 1 of each category: at least 1 fish, 1 bug, 1 fossil, etc). Once that has been done talk to Blathers when he is awake (evening).
Brewster Café: 7 days after you have upgraded the museum, donate 50 items to the museum.
Happy Home Showcase: Speak to Digby who will appear in your town on the second or third day of playing.
Dream Mansion: Speak to Isabelle 7 days after becoming mayor. It will be a Community Project and will cost 234,000 bells. You turn the money into Lloid at the train station.
Reset Surveillance Center: Quit without saving. It will show up as a Community Project costing 368,000 bells
Police Station: Talk to villagers until one request it. Will Show up as a Community Project costing 264,000 bells. You can choose from a Modern style (Copper), or a Classic style (Booker).
The Island: Have upgraded your house at least once, wait 2-3 days until Tortimer appears. The next day you will be able to travel to the island for 1,000 bells
Shovel: 500 bells at Nookling Junction
Fishing Rod: 500 bells at Nookling Junction
Net: 500 bells at Nookling Junction
Axe: 400 bells at Garden Shop
Watering Can: 500 bells at Garden Shop
Sling Shot: 500 bells at T&T Mart
Timer: 500 bells at T&T Mart
Megaphone: 500 bells at T&T Mart
Hammer: 10 medals from Island store
Silver Shovel: 500 bells at the Museum store after paying off the Community Project
Silver Fishing Rod: 500 bells at the Museum store after paying off the Community Project
Silver Net: 500 bells at the Museum store after paying off the Community Project
Silver Axe: 8 medals from the island store
Silver Watering can: Buy 50 flower bags from the garden shop
Silver Sling shot: Shoot down a silver balloon.
Gold Shovel: Buy 50 bags of fertilizer from the garden store
Gold Fishing Rod: Catch all fish and speak to Chip during the fishing tourney
Gold Net: Catch all bugs and talk to Nat during the bug catching tournament
Gold Axe: Buy 50 seedlings from the garden store
Gold Watering Can: Maintain a perfect town for 15 straight days and talk to Isabelle
Golden Slingshot: Shoot down a golden balloon.
Diving Suit: Unlock the Island. It will cost 40 medals at the island shop
Mannequins: Unlock Sable. purchase 51 pieces of clothing from Mable, purchase 31 accessories from Lablle, and you’ll receive it from Gracie when she is unlocked.
[ I hope this is helpful for some of you. If you have any questions please feel free to ask! ]
[ I want to thank Nookipedia and my copy of Tobidase Doubutsu no mori strategy guide to help me compile all this information! ]